1. Field of the Invention
This invention relates to cable testers, especially to hand-held cable testers employing voltage dividers and complementary metal oxide semiconductors for use in testing open conditions, wiring shorts, cross-wiring errors, crossing wire errors, intermittent shorts, and intermittent opens by manufacturing the cable while testing the same in a multi-cable harness.
2. Description of Prior Art
Electrical assemblies contain current paths between the components of the circuit. In many cases, these current paths consist of wires which act as conductors, transmitting an electrical signal from one part of the assembly to another or to external devices. As a general rule, the more complicated the assembly, the greater the number of signals. Consequently, complex assemblies often require a greater number of wires to conduct these signals. To simplify the manufacturing process and improve assembly serviceability, the designer of such an assembly typically organizes the various wires in groups according to their point of origin and their destination. Wires grouped in such a manner make up a fabricated assembly known as a cable harness.
Cable harnesses are manufactured in a variety of forms, depending on wire gauge, attachability, and other factors. Most cable harnesses, however, have several characteristics in common. By definition, all cable harnesses contain more than one wire. Also, cable harnesses are usually terminated by some form of connector on either end; in the case of branched cable harnesses, the harness can include many such connectors.
Whether the cable harness is constructed by human hand or through robotics, cabling errors often occur. For example a wire stressed during an automated production process can develop an open condition. A pair of neighboring wires may be shorted together when the connector is attached to the end of the cable. An assembler may cross two wires while inserting pins into the connector. Often an intermittent short or an intermittent open condition occurs. Such conditions are difficult to locate and frequently require a large expenditure of time and energy to locate.
To lower the impact of such problems on product quality, cable manufacturing facilities would benefit from a low-cost, easily-operated test apparatus that will isolate fabrication errors. Additionally, manufacturers who utilize cable harnesses in their products will benefit from such devices. In this case, the manufacturer could test the cable harness before installing it in the final assembly. Pretesting the cable harness helps minimize labor-intensive, post-production harness removals. Preinstallation tests can also shorten the final test phase for the assembly since, in the event of failure, a pretested cable can generally be eliminated as the cause. A cable test apparatus is also useful when attempting to troubleshoot an assembly in the field.
In determining whether cable testing is desirable, the manufacturer or field service planner must weigh the time required to complete the test against product quality standards, potential assembly rework costs, and repair overheads. On these grounds alone, balanced studies usually prove the advantages of performing cable tests. However, tester portability, ease of use, adaptability, cost, and other considerations can also be deciding factors.